Best way to clean out water jackets

The next time I get one cleaned, I will take pictures. The big shop I use sometimes in Macon has a new BIG ultrasonic cleaner that uses a liquid with abrasive in it. I have not had one done yet with it, but have seen the results. Aside from any pitting, when it comes out, it looks like brand new metal, inside and out. I've never seen anything like it before. This particular shop does a LOT of OTR trucks and industrial engines.